SymbOS.Cardblock.A

SUMMARY

SymbOS.Cardblock.A is a Trojan horse that affects Symbian series 60 phones.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (LiveUpdate™ Weekly) October 5, 2005
• Virus Definitions (Intelligent Updater) October 4, 2005

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low
• Causes System Instability: Sets a random password to the multimedia card of the mobile device

Distribution

• Distribution Level: Low
• Name of Attachment: instantsis.v2.1.cracked.by.binzpda.sis
• Target of Infection: Nokia Series 60 phones

TECHNICAL DETAILS

SymbOS.Cardblock.A may arrive as the file instantsis.v2.1.cracked.by.binzpda.sis. It disguises itself as a cracked version of InstantSiS application.

When SymbOS.Cardblock.A is executed, it performs the following actions:

1. Drops the following files:
   
   
   • SystemappsInstantSisClauSis.dll
   • SystemappsInstantSisInstantSis.aif
   • SystemappsInstantSisInstantSis.app
   • SystemappsInstantSisInstantSis.rsc
   • SystemappsInstantSisInstantSis.rsc.xxx
   • SystemappsInstantSisInstantSis_caption.rsc
   • SystemappsInstantSisInstantSis_caption.rsc.xxx
   • SystemappsInstantSisLicence.txt
   • SystemhelpInstantSis.hlp
     
     
2. Sets a random password to the multimedia card of the mobile device, so that the card is no longer accessible without entering the password after rebooting the phone.
   
   
3. Deletes following folders from the device:
   
   
   • C:systeminstall
   • C:systemdata
   • C:systemlibs
   • C:systemmail
   • C:systemootdata

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.

REMOVAL

1. Install a file manager program on the device.
   
   
2. Enable the option to view the files in the system folder.
   
   
3. Delete the following files:
   
   
   • SystemappsInstantSisClauSis.dll
   • SystemappsInstantSisInstantSis.aif
   • SystemappsInstantSisInstantSis.app
   • SystemappsInstantSisInstantSis.rsc
   • SystemappsInstantSisInstantSis.rsc.xxx
   • SystemappsInstantSisInstantSis_caption.rsc
   • SystemappsInstantSisInstantSis_caption.rsc.xxx
   • SystemappsInstantSisLicence.txt
   • SystemhelpInstantSis.hlp
     
     
4. Exit the file manager.